Abstract: The hollow glass microspheres were sieved to have different particle sizes, and the syntactic foams by blending hollow glass microspheres with epoxy resin were prepared. The compressive mechanical properties of the syntactic foams were studied by quasi-static compressive tests. In addition, the microscopicstructure was observed by SEM. By using the random spatial dispersing method, model of syntactic foams filled with particles having varied particle size were built. And finite element method was utilized to analyze the behavior of the matrix and particles under 1 kPa pressure. The result shows that as the particle diameter of hollow glass microspheres increases from 30 μm to 120 μm, the compressive strength of syntactic foam does not have significant change. With finite element analysis, it is found that hollow glass microspheres are the main energy loader. The value of von-Mises stress located on the hollow microspheres is higher than that of stress located on the matrix. The maximum stress is located on the inner surface of hollow glass microspheres, and it could also infer that microspheres are fully squeezed before crack from inside out with the SEM observation.